after seeing this [Fixed red X in server list if Mouse Tweaks was missing on the server] in a mouse tweeks update i started testing to see if there where any other clintside mods in my pack that has the same issue and found that this one does if not installed on server it shows red x it wont stop you from joining server but is annoying. for now i will just install this mod on server. but im assuming this is a clintside only mod and this is a bug.

Minecraft 1.16.5
Forege 36.0.22
ClientTweaks_1.16.3-5.2.0